As is known, the manufacture of circuitized substrates such as those referred to in the industry as printed circuit (or wiring) boards typically involves the precisioned alignment of individual sheets of web material known as photoresist film. Such material, when cut into individual sheet form, is then typically bonded to a base substrate which includes a dielectric material (e.g., a fiberglass-reinforced epoxy resin material commonly referred to in the industry as "FR4" material) having a layer of electrically conductive material (e.g., thin copper) bonded thereto. These members are then laminated together to form a core structure or the like which is then subjected to photolithographic processing to form the desired circuitry on the conductive layer. This resulting structure may then be populated with desired electronic devices (e.g., semiconductor chips, capacitors, resistors, etc.) to form a printed circuit (or wiring) board. Alternatively, this resulting structure may then be aligned with other, similar structure and laminated to form a multilayered structure when then may be populated, etc. during subsequent processing.
Photoresists are categorized as negative or positive and may be obtained in solid (dry film) or liquid form for application onto the aforementioned dielectric-conductor subassembly. The use of liquid (also called "wet") photoresist processing presents several problems to the manufacturer, including the need for complex controlling of liquid material flow, along with relatively complex mechanisms (e.g., rollers) for handling same. The use of dry photoresist films eliminates many of these difficulties and such films are thus more desirable from a manufacturing standpoint. It will be understood from the following that the invention is particularly directed to use of dry film photoresist materials, including those applied to an underlying dielectric-conductive layer subassembly using adhesive or the like. It is to be understood, however, that the invention is not limited to such materials, as it is readily possible to utilize the unique teachings of this invention with several other different varieties of "dry" materials (including, e.g., paper, photographic film, etc.).
There are several known methods are apparatus for handling web material, including photoresist films, as described and illustrated in the following U.S. Letters Patents:
U.S. Pat. No. 3,595,564--De Young
U.S. Pat. No. 3,680,418--Phillips
U.S. Pat. No. 3,703,116--Doll
U.S. Pat. No. 3,728,921--Vogel
U.S. Pat. No. 3,748,939--Feinstein et al
U.S. Pat. No. 3,888,066--Tabur
U.S. Pat. No. 3,965,785--Johns
U.S. Pat. No. 4,207,667--D'Angelo et al
U.S. Pat. No. 4,722,353--Weiss et al
U.S. Pat. No. 4,919,351--McNeil
U.S. Pat. No. 5,074,178--Shetley et al
U.S. Pat. No. 5,103,703--Littleton
U.S. Pat. No. 5,162,071--Nagafuchi et al
U.S. Pat. No. 5,176,784--Nagafuchi et al
U.S. Pat. No. 5,188,699--Senda
U.S. Pat. No. 5,372,670--Cummings et al
U.S. Pat. No. 5,425,834--Shinohara et al
U.S. Pat. No. 5,456,789--Boucher
Of these, particular attention is directed to U.S. Pat. No. 4,772,353 which specifically describes cutting photoresist webs using cutters (10) which engage the webs prior to board positioning. Attention is also directed to U.S. Pat. Nos. 5,425,834 and 5,456,789 where web materials are roller supplied and cut using various blade structures. Finally, attention is directed to U.S. Pat. No. 5,372,670, which is assigned to the same assignee as the present invention and is incorporated herein by reference. U.S. Pat. No. 5,372,670 defines a system for application of dry film photoresist material which in turn has been supplied from two spaced apart rollers such that the dry film will be positioned on opposite sides of the interim substrate. It is to be understood that the present invention could be utilized with this and similar structures.
A particular method of cutting dry film photoresist material involves the use of rotating, round (pizza-cutter type) cutters which cut the web material at two locations to define the sheet desired for a particular end product (circuit board). Such cutters are considered relatively expensive and maintenance-intensive, often requiring replacement. Such cutters have also proven to have a deleterious effect on the motors used to drive same, often causing motor burn out, thus adding even further to the cost of such assemblies.
It is believed that a cutting apparatus for web material such as dry film photoresist which overcomes the aforementioned disadvantages as well as those found in one or more of the foregoing several patents would represent a significant advancement in the art.